A recent study published in the Journal of Geophysical Research: Planets examines new observations made by NASA’s James Webb Space Telescope about the planet Saturn, specifically pertaining to its changing seasons. Additionally, JWST has also given astronomers a new glance into Saturn’s north pole as part of these changing seasons and is considered as follow-up research from what NASA’s Cassini spacecraft conducted during its decade-plus time in the Saturn system. these observations hold the potential to help astronomers better understand not only changing seasons on the second largest planet in the solar system, but on other gas giants, as well.
Composite image of JWST MIRI/MRS (Medium Resolution Spectroscopy) observations featuring four tiles, three on the planet and one on the rings. The filter colors represent stratospheric temperature (blue), upper tropospheric temperature (green), and lower tropospheric temperature (red) using MRS Channel 2, and the rings show all three filter colors using MRS Channel 3. (Credit: NASA, ESA, and Amy Simon (NASA-GSFC); Image Processing: Alyssa Pagan (STScI))
“The quality of the new data from JWST is simply breath-taking – in one short set of observations, we’ve been able to continue the legacy of the Cassini mission into a completely new Saturnian season, watching how the weather patterns and atmospheric circulation respond to the changing sunlight,” said Dr. Leigh Fletcher, who is a Professor of Planetary Science at the University of Leicester and lead author of the study.
Since Saturn’s orbit is 30 years long, each season lasts approximately 7.5 Earth years, with its northern autumn equinox beginning in 2025. For context, Earth’s northern autumn equinox is beginning right now, which means polar winter is beginning on the north poles of both worlds, though Earth is a small rocky planet and Saturn is a much larger gas planet.
For the study, the researchers used JWST’s Mid-Infrared Instrument (MIRI) to examine Saturn’s atmosphere and its north polar cyclone (NPC), which was first observed by the Cassini spacecraft in 2006 with better observations occurring in 2009 when the NPC was better lit by the Sun. Other measurements obtained by this most recent study include gaseous abundances and temperatures within the rest of the atmosphere. While the NPC appears blue in infrared now, it will start to cool down as Saturn’s long autumn approaches before disappearing completely for the duration of the autumn season.
What makes this study unique is Cassini was only able to observe Saturn up-close during the planet’s northern winter and spring, so these new observations offer better insights into the gas giant’s seasonal cycles and how it affects the planet, overall. The results of these observations indicate that cloud circulation within Saturn’s stratosphere has reversed course with cooler stratospheric temperatures being observed, which suggests that cooler air will be flowing towards the equator soon. Essentially, the researchers are conducting meteorology on another planet, in this case, a gas giant planet.
“No spacecraft has ever been present to explore Saturn’s late northern summer and autumn before, so we hope that this is just the starting point, and that JWST can continue the legacy of Cassini into the coming decade,” said Dr. Fletcher.
As always, keep doing science & keep looking up!
Sources: Journal of Geophysical Research: Planets, EurekAlert!, University of Leicester, NASA
